This invention relates generally to an electrostatographic printer or copier, and more particularly concerns a flexible belt cleaning apparatus used therein.
In an electrophotographic application such as xerography, a charge retentive surface (i.e., photoconductor, photoreceptor or imaging surface) is electrostatically charged, and exposed to a light pattern of an original image to be reproduced to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on that surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable powder referred to as "toner". Toner is held on the image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate (eg., paper), and the image affixed thereto to form a permanent record of the image to be reproduced. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. The process is well known, and useful for light lens copying from an original, and printing applications from electronically generated or stored originals, where a charge surface maybe imagewise discharged in a variety of ways. Ion projection devices where a charge is imagewise deposited on a charge retentive substrate operates similarly.
Although a preponderance of the toner forming the image is transferred to the paper during transfer, some toner invariably remains on the charge retentive surface, it being held thereto by relatively high electrostatic and/or mechanical forces. Additionally, paper fibers, Kaolin and other debris have a tendency to be attracted to the charge retentive surface. It is essential for optimum operation that the toner remaining on the surface be cleaned thoroughly therefrom.
A commercially successful mode of cleaning employed on automatic xerographic devices utilizes a brush with soft conductive fiber bristles or with insulative soft bristles which have suitable triboelectric characteristics. While the bristles are soft for the insulative brush, they provide sufficient mechanical force to dislodge residual toner particles from the charge retentive surface. In the case of the conductive brush, the brush is usually electrically biased to provide an electrostatic force for toner detachment from the charge retentive surface. The fixed radius of commonly used brushes can limit it's cleaning applications. Also, maintaining the fibers of the cleaning brush in constant contact with the imaging surface accelerates set of the brush at the cleaning nip.
The following disclosures may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 4,567,905 to Stewart et al. discloses a slideable control for use in retractable bristle brushes. The control operates by co-action with a rotatable cylindrical mandrel carrying pivoted bristles and having an angular cam slot. The control includes a longitudinally slideable button in the handle which has a control.
U.S. Pat. No. 4,551,217 to King discloses two electrodes of an apparatus are concentrically disposed one within the other and two sets of scrubbing brushes are utilized, one mounted on the stationary electrode for cleaning the inner, rotary electrode and the other mounted on the rotary electrode itself for cleaning the stationary electrode during such rotation. A cam arrangement momentarily retracts one of the brushes out of the path of travel of the other during each revolution to avoid having the two brushes strike one another.
U.S. Pat. No. 4,001,910 to Pellet discloses retractable brushes, of the general type having bristles which can be retracted into the casing of the brush, or moved outwardly from the casing into the position at which the bristles are used.
U.S. Pat. No. 3,819,263 to Draugelis et al. discloses rotating a housing from its non-operative position wherein the brush is spaced approximately one inch from a transfer roll to its operative position wherein the brush contacts the surface of transfer roll to dislodge residual toner particles remaining thereon.